There are approximately 600 kinds of carotenoids naturally, but only six kinds of these have so far been produced industrially such as production by Roche Corporation and BASF Corporation. Lycopene as an important product has important functions on scavenging free radical, antiageing, inhibiting tumor, treating heart attack and so on (H. Gerster, J., Am. Coll. Nutr. 1997, 16, 109; Nutr. Cancer 1995, 24.257; E. Giovannucci. et al. J. Natl. Cancer Inst. 1995, 87, 1767; Chem. Abstracts 1990, 112 91375w), and is widely used for medicines, food additives, feed additives. Roche Corporation develops a synthesis route by the Witting Reaction, wherein it uses expensive and poisonous raw materials such as tri-phenyl phosphorous (K. Meyer, et al., Helv. Chim. Acta 1992, 75.1848). Other former synthesis methods use tri-phenyl phosphorous either (P. Karrer, et al., Helv. Chim. Acta 1950, 33, 1349; B. C. L. Weedon, et al., J. Chem. Soc. 1965, 2019; K. Bernhard and H. Mayer, Pure & Appl.-them. 1991,63, 35).
It has been reported from Publication No. WO 0031086, (2000-06-02) of PCT application that Babler J. H. et al. developed a new method of synthesizing lycopene by the Wittig-Horner Reaction, wherein 3,7,11-trimethyl-2,4,6,10-dodecatetraenyl phosphonic acid diethyl ester of formula (5) as a crucial intermediate undergoes a condensation reaction with decyl di-aldehyde (8) by catalysis of bases for preparing lycopene, the whole synthesis sequence is described as follows.
Firstly, pseudoionone (2) reacts with ethynyl anion to produce tertiary alcohol (7) (3,7,11-trimethyl-4,6,10-dodecatrien-1-yn-3-ol):

Afterwards, tertiary alcohol (7) reacts with dialkyl chlorophosphite to produce propadiene pentadecyl phosphoric acid ester (6) (3,7,11-trimethyl-1,2,4,6,10-dodecapentaenyl phosphoric acid diethyl ester).

Secondly, propadiene pentadecyl phosphoric acid ester (6) is partially reduced and transformed to pentadecyl phosphoric acid ester (5) (3,7,11-,trimethyl-2,4,6,10-dodecatetraenyl phosphoric acid diethyl ester):

Finally, pentadecyl phosphoric acid ester (5) undergoes a condensation reaction with decanal di-aldehyde (8) (2,7-dimenthyl-2,4,6-octatriene-1,8-dial) by catalysis of bases to obtain lycopene (1).

The method uses a new compound 2,4,6,10-pentadecatetraenyl phosphoric acid ester (5) as an intermediate to avoid uses of triphenyl phosphorous; and moreover uses pseudoionone as a raw material to obtain products of lycopene by reactions of four steps. The synthesis route thereof is concise, and has prominent improvement relative to former methods. However there are some problems in the method. Firstly it is difficulty for reactions of tertiary alcohol (7) with dialkyl chlorophosphite to produce propadiene pentadecyl phosphoric acid ester (6). Secondly it is hard to handle the reduction technology of propadiene pentadecyl phosphoric acid ester (6) selectively being reduced to pentadecyl phosphoric acid ester (5).
Recently, the Chinese patent application No. 2010101042817 of Runbo SHEN et. al. discloses a method of preparing lycopene (1) by a condensation reaction of Wittig-Horner between 1,4,6,10-tetra-double bond pentadec-carbon phosphonate of formula (4) (3,7,11-,trimethyl-1,4,6,10-dodecatetraenyl phosphoric acid diethyl ester) and decanal di-aldehyde (8). The synthesis route of the method comprises the following reaction sequence:

The method of preparing the key intermediate C-14, aldehyde[2,6,10-trimethyl-3,5,9-undecatrienyl-1-aldehyde of formula (3)] refers to the U.S. Pat. No. 4,000,131 (Rosenberger, et al., Oct. 28, 1976). That is, 2,6,10-trimethyl-3,5,9-undecatrienyl-1-aldehyde of formula (3) is obtained by reaction of pseudoionone (2) reacts with sulfonium salt to produce epoxide, and then the epoxide is catalyzed to open a loop to obtain 3-position double bond of formula (3), 2,6,10-trimethyl-3,5,9-undecatrienyl-1-aldehyde. However this method has deficiencies of expensive iodomethane, polluted dimethyl sulfide and dangerous DMSO sodium, and is difficult to apply for industrial production.